1. Field of the Invention
Embodiments of the present invention relate to providing inductive power in wet environments. In particular selected embodiments relate to inductive power outlets incorporated into water resistant work-tops and inductive power receivers incorporated into water resistant electrical devices.
2. Background Art
The provision of electric power where and when needed, is an important consideration when constructing buildings. The number and location of power outlets required for each room is dependent upon how the room will be used. Often, however, the future function of the room is not known during its construction. Consequently, it is often necessary to relocate power outlets long after a building is completed, which can be costly.
Conventional power outlets are typically situated at strategic points around the walls of rooms. A ring main to which the power sockets are connected may be provided. Such a ring main typically runs around a conduit pipe embedded in the wall, and electrical boxes in/on the wall are connected therewith. The location of power outlets is thus determined by the locations of the fixed electrical boxes. Once the wall has been finished, the relocation of power outlets is difficult.
In order to add or relocate power outlets, additional wiring must be provided. The additional wiring may itself be embedded into the wall by chiseling a groove into the surface thereof, running the wiring along the groove and rendering over the wiring, with plaster, pointing compound or the like. Additional power outlets are typically either sunk into depressions cut into the wall surface or alternatively, protruding electrical boxes are screwed or bolted there onto. Another method for relocating power outlets is to attach a power conduit to the outside of the wall and to run wiring through the external conduit, with power outlets being connected to the external conduit. Such a solution is commonly used in schools, colleges, laboratories and other institutions, particularly where the walls are constructed from solid stone, concrete or brick. It will be appreciated that this solution is costly, time consuming and unsightly.
U.S. Pat. No. 3,585,565 to Price describes an electrical tape and plug connector designed to facilitate and simplify the installation of electrical wiring. Substantially flat or film conductors are sandwiched between insulating layers of protective material. The sandwich construction includes a ground conductor insulated from the two mains current carrying conductors. One surface or side of the tape or cable is coated with a pressure-sensitive adhesive. A three-prong connector adapts the tape or cable to a utility outlet.
Price's solution allows wiring to lie flat against a wall surface which makes the wiring less obtrusive and simpler to install. However installation of the utility outlets requires the removal of insulation from the conducting tape and the connection of a special plug. Furthermore, the utility outlet once connected cannot be removed without exposing the bared conductor.
An alternative system is described in United States Patent Application No. 2002/0084096 to Chang. Chang describes an electric wire coupling device which includes one or more electric wires having one or more electric cables engaged and received in an outer rubber covering. One or more sockets each has a socket housing and two conductor members secured in the socket housing, which are aligned with the orifices of the socket housing for receiving plugs. The electric wires and/or the sockets each has an adhesive material for attaching to the supporting wall without further fasteners. The socket may include a side opening for coupling to the other electric wires.
In Chang's system the power strip and outlets are stuck onto a wall surface and protrude there from. Aside from being unsightly, if the protruding sockets are knocked they may become detached from the wall. Because the sockets and wires are supported only by the adhesive and not by additional fasteners, if the sockets become detached from the wall they will only be supported by the wire itself, thereby posing a safety hazard.
Conventional electrical sockets have holes therein into which the pins of corresponding plugs are inserted to form a conductive coupling. For safety, the power supplying side of the couple is generally the female part, and does not have bare conductive elements protruding there from. The plug coupled to the device is the corresponding male part, typically having bare pins. The size of the pins and holes are such that even a small child cannot insert his or her fingers thereinto. In high quality sockets, an earth connection is provided, and, only when a plug with a longer earth pin is inserted there into, is it possible to insert a pin (or anything else) into the holes connected to the current carrying live and neutral wires. Nevertheless, children do occasionally manage to insert pencils, pins and other objects into socket holes, sometimes with fatal results. Water can also cause shorting and may result in electrocution.
Since sockets are unsightly, the number of sockets installed on a wall is generally limited. Often, their position is not appropriate to changing requirements and extension leads are needed.
Inductive power coupling allows energy to be transferred from a power supply to an electric load without connecting wires therebetween. The power supply is wired to an inductive power outlet including a primary inductor across which an oscillating electric potential is applied thereby inducing an oscillating magnetic field therearound. The oscillating magnetic field may induce an oscillating electrical current in a secondary inductor, placed therewithin. In this way, electrical energy may be transmitted from the primary inductor to the secondary inductor by electromagnetic induction without the two inductors being conductively connected. When electrical energy is transferred from a primary inductor to a secondary inductor the pair are said to be inductively coupled.
Electrical devices may be adapted to draw energy from inductive power outlets by wiring their electric loads to such secondary inductors. Inductive power provision is particularly useful in wet environments, such as in a laboratory, kitchen or bathroom, where conventional power sockets may be hazardous.
For these and other reasons, there is a need for alternative power provision than occasionally positioned, conventional socket outlets along a wall and the present invention addresses this need.